Assemblies comprising fastener with ergonomically balanced removal to insertion ratio

ABSTRACT

This invention relates to a spring fastener, which comprises engagement springs in opposite sides of the fastener. Each engagement spring has an engagement region comprising a hindrance portion, which increases considerably the removal to insertion force ratio as compared to such ratio in the absence of the hindrance portion, thus permitting very easy insertion with considerably more difficult removal of the fastener from the slot of a panel, which provides an efficient ergonomically balanced removal to insertion force ratio. The hindrance portion comprises ripples or other hindrance elements of unexpectedly minute dimensions for providing this efficient ergonomic force balance.

RELATED APPLICATIONS

[0001] This application claims priority of provisional patentapplications 60/301,364, filed Jun. 25, 2001, 60/327,814, filed Oct. 9,2001, and 60/353,515, filed Feb. 1, 2002, all three of which areincorporated herein by reference in their entirety.

FIELD OF THE INVENTION

[0002] This invention relates to spring fasteners characterized by astructure having a cavity in which an extension or rib of a first part,such as a plastic panel for example, may be engaged, and they are alsosuitable to be engaged reversibly in a slot of second part, such as ametal sheet or the frame of a car for example. The invention alsopertains an assembly of the first and the second part as connected toeach other through the fastener, as well as vehicles comprising suchassemblies.

BACKGROUND OF THE INVENTION

[0003] A number of fasteners have been used in the past for securing oneobject on another object, as for example, securing an article such asfor example a plastic sheet on a metal or other rigid plastic sheet.However, the fasteners of the type, which are improved by the advancesof the present invention, and being used presently, have a rather lowratio of insertion force to removal force. In other words, they requireconsiderable force to be inserted into a slot in order to provideadequate removal resistance in order to be removed from the slot. Thisis ergonomically inferior performance, and the operators may suffermiscellaneous ailments, while productivity is also considerablyundermined.

[0004] Examples of conventional fasteners are disclosed in U.S. Pat. No.5,987,714 (Smith); U.S. Pat. No. 5,887,319 (Smith); U.S. Pat. No.5,542,158 (Gronau et al.); U.S. Pat. No. 5,422,789 (Fisher et al.), U.S.Pat. No. 5,373,611 (Murata); U.S. Pat. No. 5,314,280 (Gagliardi); U.S.Pat. No. 5,095,592 (Doerfling); U.S. Pat. No. 4,792,475 (Bien U.S. Pat.No. 4,683,622 (Ohelke); U.S. Pat. No. 4,609,170 (Schnabl); U.S. Pat. No.4,245,652 (Kelly et al.); U.S. Pat. No. 3,864,789 (Leitner); U.S. Pat.No. 3,673,643 (Kindell); U.S. Pat. No. 3,525,129 (Holton), U.S. Pat. No.2,825,948 (Parkin); U.S. Pat. No. 2,607,971 (Bedford, Jr.); U.S. Pat.No. 2,542,883 (Tinnerman); U.S. Pat. No. 2,329,688 (Bedford, Jr.); U.S.Pat. No. 2,322,656 (Murphy), among others.

[0005] U.S. Pat. No. 5,919,019 (Fisher) provides fasteners which canonly be permanently installed into a slot; they can only be inserted butnot extracted without damage to parts of the fastener. The majorengagement is performed by spring strips, while frictional portions ofthe fastener pass through the slot with at most slight compression, andimmediately after the insertion of the fastener they are located inslightly spaced or barely contacting relation with the edges of theslot. They are only activated for engagement after the insertion of abolt into a hole at the base plate. Thus, the profound effect of theincreased removal to insertion ratio (explained in detail hereinbelow)is not recognized, mentioned, or implied. Thus, the intentionallyprovided distance of the frictional portions away from the edges of theslot by Fisher, during insertion and before use of the bolt, teachesactually away from the instant invention, which recognizes and takesfull advantage of the increased removal to insertion ratio by anengagement region having a hindrance portion. As a matter of fact, ifthe engagement surfaces of the instant invention were located inslightly spaced or barely contacting relation with the edges of theslot, no engagement at all would take place upon insertion of thefastener of this invention into the slot.

[0006] U.S. Pat. No. 6,141,837 (Wisniewski) describes a spring fastenercomprising bulbous and outwardly projecting portions, which assist inpreventing withdrawal of the clip and associated molding from anaperture of a vehicle frame. However, “bulbous projections” arenecessarily voluminous, take most of the space between the “reversebents”, and unless they are manufactured within tight tolerances withregard to the thickness of the frame, the “base plates” do not sit onthe frame (see also the Figures), rendering the structure unstable.

[0007] U.S. Pat. Nos. 6,203,240 B1 (Hironaka et al.), 5,129,768 (Hoyleet al.), 5,092,550 (Bettini), 4,981,310 (Belissaire), 4,712,341 (Harris,Jr. et al.), 4,595,325 (Moran et al.), 4,431,355 (Junemann), 4,133,246(Small), and 2,424,757 (F. Klump, Jr.) are directed to plastic or metalfasteners which are designed to be just inserted into the slot of apanel, but not extracted without damage to the fastener (if suchextraction would be attempted from the front side; the side from whichthe fastener is inserted into the panel, since the back part of thepanel is not reachable in the cases, wherein such types of fasteners areused).

SUMMARY OF THE INVENTION

[0008] As aforementioned, this invention relates to spring fastenerscharacterized by a structure having a cavity in which the rib of a firstpart, such as a plastic panel for example, may be engaged, and they arealso suitable to be engaged reversibly in a slot of second part, such asa metal sheet or the frame of a car for example. The invention alsopertains an assembly of the first and the second part as connected toeach other through the fastener, as well as vehicles comprising suchassemblies.

[0009] More particularly, the invention pertains a spring fastenercomprising a first side and a second side opposite the first side, thefirst side connected to the second side thereby forming a U-shapedstructure having a cavity between the first side and the second side, abottom portion wherein the first side and the second side are connected,and a top portion, the first side comprising first barbs having firstfront ends, and a first engagement spring, the first engagement springconnected to the first side in the vicinity of the bottom portion, thesecond side comprising second barbs second front ends, and a secondengagement spring, the second engagement spring connected to the secondside in the vicinity of the bottom portion, each of the first and secondengagement springs having a recess and a free end in the vicinity of thetop portion, each spring also comprising a peak and an engagement regionwith a hindrance portion between the recess and the peak, the hindranceportion providing increased removal force, when the fastener is pulledby a rib of a first part engaged to the first and second barbs, afterthe fastener has been inserted into a slot of a second part, the slothaving a slot width and edges on which edges the engagement region isengaged, the increased removal force being due to the hindrance portion,and wherein the fastener can be extracted when pulled by the rib withoutdamage to said fastener.

[0010] This invention further pertains an assembly comprising:

[0011] a spring fastener comprising a first side and a second sideopposite the first side, the first side connected to the second sidethereby forming a U-shaped structure having a cavity between the firstside and the second side, a bottom portion wherein the first side andthe second side are connected, and a top portion, the first sidecomprising first barbs having first front ends, and a first engagementspring, the first engagement spring connected to the first side in thevicinity of the bottom portion, the second side comprising second barbssecond front ends, and a second engagement spring, the second engagementspring connected to the second side in the vicinity of the bottomportion, each of the first and second engagement springs having a recessand a free end in the vicinity of the top portion, each spring alsocomprising a peak and an engagement region with a hindrance portionbetween the recess and the peak;

[0012] a first part comprising a rib inserted into the cavity of thespring fastener and engaged to the first and second barbs; and

[0013] a second part comprising a slot, the slot having a width andedges, the fastener being disposed in the slot in a manner that theedges of said slot are engaged to the engagement regions of the springfastener;

[0014] with the requirement that by pulling the rib, the fastener isextracted from the slot without damage to the fastener, and with ahigher force than a force required in the absence of the hindranceportion.

[0015] In addition, this invention is related to a vehicle whichcomprises an assembly, the assembly comprising vehicle comprising anassembly, the assembly comprising:

[0016] a spring fastener comprising a first side and a second sideopposite the first side, the first side connected to the second sidethereby forming a U-shaped structure having a cavity between the firstside and the second side, a bottom portion wherein the first side andthe second side are connected, and a top portion, the first sidecomprising first barbs having first front ends, and a first engagementspring, the first engagement spring connected to the first side in thevicinity of the bottom portion, the second side comprising second barbssecond front ends, and a second engagement spring, the second engagementspring connected to the second side in the vicinity of the bottomportion, each of the first and second engagement springs having a recessand a free end in the vicinity of the top portion, each spring alsocomprising a peak and an engagement region with a hindrance portionbetween the recess and the peak;

[0017] a first part comprising a rib inserted into the cavity of thespring fastener and engaged to the first and second barbs; and

[0018] a second part comprising a slot, the slot having a width andedges, the fastener being disposed in the slot in a manner that theedges of said slot are engaged to the engagement regions of the springfastener;

[0019] with the requirement that by pulling the rib, the fastener isextracted from the slot without damage to the fastener, and with ahigher force than a force required in the absence of the hindranceportion.

[0020] According to this invention, and particularly for ergonomicpurposes combined with practical aspects, it is highly preferable thatthe force to insert the rib of the first part into the cavity of thespring fastener should be less than 40 lbs, preferably less than 15 lbs,and even more preferably less that 10 lbs; the force to insert thespring fastener into the slot should be less that 30 lbs, preferablyless than 15 lbs, and even more preferably less than 10 lbs; and theforce to extract the spring fastener from the slot should be in therange of 30-100 lbs, and preferably in the range of 50-70 lbs.

[0021] To achieve the above results, in a preferred embodiment of thisinvention, the hindrance portion comprises one structure selected fromripple, side rib, upward solid bent extension parallel to the peak andthe recess, knurled region, bent teeth, each having a depth, and acombination thereof.

[0022] It is preferable that the depth of the ripple, the side rib, theupward solid bent extension which is parallel to the peak, the knurledregion, and the bent teeth is smaller than 0.2 mm.

[0023] It is further preferable that each ripple is in the form of adepression, the depression having a deepest part, a front side, a backside and a width, and the hindrance portion has a surface, comprises notmore than three ripples, and wherein the depth of each ripple is thedistance between the surface of the hindrance portion and the deepestpart of the respective ripple.

[0024] It is more preferable that the hindrance portion comprises notmore than two ripples, and even more preferable one ripple.

[0025] For better performance, the ripple width is larger than the depthof the ripple, and preferably the ripple width is at least twice thesize of the depth of the ripple.

[0026] The ripple width is preferably in the range of 0.1 to 0.5 mm andthe ripple depth is in the range of 0.01 to 0.1 mm.

[0027] In a preferred embodiment, the back side of the ripple has aslope in the range of 15 to 30 degrees with regard to the general planeof the hindrance portion, and it is also preferable that the front sidehas a higher slope than the back side.

[0028] In the case that the hindrance portion comprises a single ripple,it is highly preferable that the ripple has only a back side, andsubstantially lacks a front side. It is also highly preferable that theback side has the form of a curvature with a gradually decreasing slope.For example, the gradually decreasing slope may have the shape of an arcin the range of 50-70 degrees with a radius in the range of 0.03-0.05mm.

[0029] The barbs are preferably selected from a group consistingessentially of:

[0030] first barbs being outer barbs and second barbs being inner barbs;

[0031] first barbs being outside outer barbs and second barbs beinginside outer barbs; and

[0032] first barbs being inner barbs and second barbs being inner barbs.

[0033] It is preferable that the barbs are cut from their respectiveside, are flexible, and bent in the vicinity of their respective frontend as described for example in U.S. Pat. No. 6,279,207 B1, which isincorporated herein by reference, and more particularly in FIG. 1 ofsaid patent, with an angle of bent in the range of 5-25 degrees.

[0034] The barbs are considered to be flexible if they do not cause thewidth W3 (FIG. 1A) to increase more than 30%, preferably 20%, and morepreferably 10%, when the rib 46 is inserted into the cavity 19 of thefastener 10 (FIG. 4A), and provided that the first object 46 isadequately hard to hinder the barbs 36 from substantially digging intoit.

[0035] Regarding the outside outer barbs, it is preferable that theirfront points are at a distance from the second side smaller than thethickness of the material from which the spring fastener was made. Thisis to avoid interconnection of the fasteners, when said fasteners arestored in bulk.

[0036] The barbs may have variable width along their length, or they mayhave substantially the same width along their length. Further, the frontpoints of the barbs may be toothed.

[0037] It is also preferable that the fastener has a width in thevicinity of the top portion of the fastener which is at least 60%, andmore preferably at least 70%, as wide as the slot width.

[0038] With respect to the engagement region it is preferable that it isat least partially wider than the rest of the engagement spring.

[0039] The spring fasteners of the instant invention may have twoengagement springs at the edges of each side instead of one engagementspring in substantially the middle portion of each side.

[0040] The spring fastener may further comprise additional lower barbspointing inwardly and originating form the vicinity of the bottomportions of the first side and the second side of the fastener. Inanother embodiment, each side of the spring fastener has only one upperbarb and one lower barb, the upper barb of one side facing the lowerbarb of the other side and vice versa. In still another embodiment, thefastener may further comprise a relief opening in the vicinity of thebottom of the spring fastener.

[0041] The spring fastener of the instant invention may further comprisea molded elastic body under the top portion of said spring fastener.Such arrangements are disclosed in U.S. Pat. No. 6,353,981 B1, which isincorporated herein by reference.

[0042] In another embodiment, the spring fastener of the instantinvention may further comprise:

[0043] an elastic body comprised of at least a gasket, the gasketextending away from the closed cavity in the vicinity of the top portionof the fastener and enclosing at least partially the cavity; and

[0044] a casing surrounding at least partially the spring fastener underthe top portion, except at least the engagement section of eachengagement spring, the casing also at least partially surrounding thecavity and such portion of the elastic body which at least partiallyencloses the cavity;

[0045] wherein the casing has lower ultimate elongation, higher Shorehardness, and higher shear strength than the elastic body.

[0046] Such arrangements are disclosed in U.S. Pat. No. 6,381,811 B2,which is incorporated herein by reference

[0047] According to the present invention, any embodiments of fastenersdescribed above and their equivalents may be used in any assembly inwhich the first part and the second part are connected with thefastener, as well as in any vehicle comprising such an assembly or sucha fastener or its equivalents.

DESCRIPTION OF THE DRAWING

[0048] The reader's understanding of practical implementation ofpreferred embodiments of the invention will be enhanced by reference tothe following detailed description taken in conjunction with perusal ofthe drawing figures, wherein:

[0049]FIG. 1 illustrates a perspective view of a spring fasteneraccording to a preferred embodiment of the present invention, whereinthe hindrance portion comprises a single-sided ripple and bent barbs.

[0050]FIG. 1A shows a side view of the spring fastener of FIG. 1.

[0051]FIG. 2 illustrates a perspective view of a spring fasteneraccording to another preferred embodiment of the present invention,wherein the hindrance portion comprises one two-sided ripple and bentbarbs.

[0052]FIG. 3A illustrates a fragmental cross-sectional view of anengagement spring, wherein the hindrance portion comprises asingle-sided ripple.

[0053]FIG. 3B illustrates a fragmental cross-sectional view of anengagement spring, wherein the hindrance portion comprises one two-sidedripple.

[0054]FIG. 3C illustrates a fragmental cross-sectional view of anengagement spring, wherein the hindrance portion comprises two two-sidedripples.

[0055]FIG. 3D illustrates a fragmental cross-sectional view of anengagement spring, wherein the hindrance portion comprises threetwo-sided ripples.

[0056]FIG. 4 illustrates two parts, which can be connected with thefastener according to the present invention.

[0057]FIG. 4A illustrates the side view of the fastener of FIG. 1 and across section of the rib of a first part, such as a panel for example,inserted into the cavity of the fastener.

[0058]FIG. 4B illustrates the same elements shown in FIG. 4A afterinsertion of the fastener into the slot of a second part, such as theframe of an automobile for example.

[0059]FIG. 4C illustrates a fragmental cross section of the second partof FIG. 4B and the edges of the slot in relation with the engagementregions of the engagement springs of the fastener.

[0060]FIG. 5 illustrates a detailed diagram of a ripple in the hindranceportion according to preferred embodiments of the instant invention.

[0061]FIG. 5A illustrates a detailed diagram of a single-sided ripplehaving a back side in the form of a curvature in the hindrance portionaccording to a highly preferred embodiment of the instant invention.

[0062]FIG. 6 illustrates a stamped fastener before final formationaccording to another embodiment of the present invention, wherein thefastener comprises outer and inner barbs, as well as relief portions inthe vicinity of the bottom of the fastener.

[0063]FIG. 6A illustrates a side view of the fastener of FIG. 6 afterfinal formation.

[0064]FIG. 7 illustrates a stamped fastener before final formationaccording to another embodiment of the present invention, wherein thefastener comprises outside outer barbs on the first side and insideouter barbs on the second side.

[0065]FIG. 8 illustrates a stamped fastener before final formationaccording to another embodiment of the present invention, wherein thefastener comprises only inner barbs.

[0066]FIG. 9 illustrates a stamped fastener before final formationaccording to another embodiment of the present invention, wherein thefastener comprises upper and lower outer and inner barbs.

[0067]FIG. 10 illustrates a stamped fastener before final formationaccording to another embodiment of the present invention, wherein thefastener comprises two engagement springs per side of the fastener, andonly one upper and one lower barb per side.

[0068]FIG. 11 illustrates a stamped fastener before final formationaccording to another embodiment of the present invention, wherein thebarbs have uniform width along their length.

[0069]FIG. 11 illustrates a stamped fastener before final formationaccording to another embodiment of the present invention, wherein thebarbs have uniform width along their length, and they are toothed attheir front ends.

[0070]FIG. 13 illustrates a cross-sectional view of the middle portionof a spring fastener, according to another embodiment of the instantinvention, wherein a molded elastic body 54 is disposed at least underthe top portion of said spring fastener.

[0071]FIG. 14 is a perspective view of a fastener, according to stillanother embodiment of the instant invention, wherein the lower portionof the fastener is covered by a casing, while an elastic body isdisposed in the vicinity of the top portion and encloses the cavity, atleast partially.

DETAILED DESCRIPTION OF THE INVENTION

[0072] As aforementioned, this invention relates to spring fastenerscharacterized by a structure having a cavity in which the rib of a firstpart, such as a plastic panel for example, may be engaged, and they arealso suitable to be engaged reversibly in a slot of second part, such asa metal sheet or the frame of a car for example. The invention alsopertains an assembly of the first and the second part as connected toeach other through the fastener, as well as vehicles comprising suchassemblies.

[0073] More particularly, as better shown in FIGS. 1 and 1A, theinvention pertains a spring fastener 10 comprising a first side 12 and asecond side 14 opposite the first side 12. The first side 12 isconnected to the second side 14 forming a U-shaped structure which has acavity 19 between the first side 12 and the second side 14. The fastener10 also has a bottom portion 16, wherein the first side 12 and thesecond side 14 are connected. It further has a top portion 18 a and 18 b(collectively 18).

[0074] In all cases, numerals referring to the first side 12 contain theletter “a”, while numerals referring the second side 14 contain theletter “b”. The same numerals without the letters “a” or “b”, refercollectively to the respective elements of both sides.

[0075] The first side 12 comprises first barbs 36 a, which in this caseare outer barbs, since they are disposed in an outer portion of thefirst side 12. The barbs 36 a have first front ends 38 a. In thisparticular case the first barbs 36 a are bent inwardly in the vicinityof the front ends 38 a, as it will be explained in more detail at alater point.

[0076] The first side 12 also comprises a first engagement spring 20 a,which is connected to the first side 12 in the vicinity of the bottomportion 16.

[0077] The second side 14 comprises second barbs 36 b, which in thiscase are inner barbs, since they are disposed in an inner portion of thesecond side 14. The second barbs have second front ends 38 b. In thisparticular case the first barbs 36 b are also bent inwardly in thevicinity of the front ends 38 b, as it will be explained in more detailat a later point.

[0078] The second side 14 comprises a second engagement spring 20 b,which is connected to the second side 14, also in the vicinity of thebottom portion.

[0079] Each of the first and second engagement springs 20 a and 20 bhave a first and second recess, 24 a and 24 b, respectively, and a firstand second free end, 22 a and 22 b, respectively, in the vicinity of thetop portion 18 (18 a and 18 b, respectively). Each spring also comprisesa first and a second peak, 26 a and 26 b, respectively, and a first andsecond engagement region, 28 a and 28 b, respectively, with a first andsecond hindrance portion, 29 a and 29 b, respectively, between therecesses 24 and the peaks 26.

[0080] The hindrance portions providing increased removal force, whenthe fastener 10 is pulled by a rib or extension 46 (FIG. 4B) of a firstpart 44 (FIG. 4) engaged to the first and second barbs, 36 a and 36 b,respectively, after the fastener 10 has been inserted into a slot 50 ofa second part 48 (FIG. 4), the slot 50 having a slot width W2 (FIGS. 4and 4C) and edges 51 (FIG. 4C) on which edges the engagement regions 28a and 28 b are engaged. The increased removal force is due to thehindrance portions 29 a and 29 b (FIG. 4C), which in this particularcase comprise single ripples with only back sides 34, as it will beexplained at a later point in more detail. According to this invention,the engagement portions 28 a and 28 b and the hindrance regions 29 a and29 b are required to be such that the fastener 10 can be extracted fromthe slot 50 when pulled by the rib 46 without damage to said fastener10, and with a higher force than a force required in the absence of thehindrance portions 29 a and 29 b.

[0081] This invention further pertains an assembly 11, as better shownin FIG. 4B, comprising a spring fastener as described above or in theembodiments presented hereinbelow; a first part 44 (FIG. 4) comprising arib 46 (FIG. 4A) inserted into the cavity 19 of the spring fastener 10and engaged to the first and second barbs 36 a and 36 b; and a secondpart 48 (FIGS. 4 and 4B) comprising a slot 50, which slot 50 has a widthW2 and edges 51 (FIG. 4C), so that the edges 51 of said slot are engagedto the engagement regions 28 a and 28 b of the spring fastener 10. Inthis case also, the requirement exists that by pulling the rib 46, thefastener 10 is extracted from the slot 50 without damage to the fastener10, and with a higher force than a force required in the absence of thehindrance portions 29 a and 29 b.

[0082] In addition, this invention is related to a vehicle whichcomprises an assembly 11, as described above.

[0083] In operation of the above embodiments, the spring fastener 10 ofthe present invention is intended to connect a first part, such as apanel 44 for example, which panel may have a rib 46, with a second part,such as a frame 48 of a car for example, having a slot 50, asillustrated in FIG. 4.

[0084] The rib 46 of the panel 44 is preferably first inserted into thecavity 19 of the fastener 10 (see FIG. 4A), where, it is secured bybarbs 36 a and 36 b. Then, the fastener 10, which has been secured onthe extension 46 of the panel 44, is inserted into the slot 50 of theframe 48, as better shown in FIG. 4B.

[0085] In this manner, the first part, exemplified by panel 44, has beenconnected on the second part, exemplified by frame 48, through thefastener 10 of the instant invention.

[0086] In most practical applications, the length Le (see FIG. 4A) ofthe engagement regions 28 is not higher than 2-4 mm, while the thicknessT_(f) of the frame 48 (see FIG. 4B) may vary in most occasions in therange of 0.5 to 2 mm. This fact makes it rather difficult to form largehindrance portions. Thus, The “bulbous projections” suggested by U.S.Pat. No. 6,141,837 (Wisniewski) are necessarily too bulky andvoluminous, take most of the space between the “reverse bents”(engagement regions between the peak and the recess in the case of theinstant invention), and unless they are manufactured within tighttolerances with regard to the thickness of the frame (which in practicemay vary considerably), the “base plates” (top portions in the case ofthe present invention) do not sit on the frame (see also Wisniewski'sFigures), rendering the structure considerably unstable.

[0087] According to this invention, and particularly for ergonomicpurposes combined with practical aspects, it is highly preferable thatthe force to insert the rib of the first part into the cavity of thespring fastener should be less than 40 lbs, preferably less than 15 lbs,and even more preferably less that 10 lbs; the force to insert thespring fastener into the slot should be less that 30 lbs, preferablyless than 15 lbs, and even more preferably less than 10 lbs; and theforce to extract the spring fastener from the slot should be in therange of 30-100 lbs, and preferably in the range of 50-70 lbs.

[0088] It was unexpectedly found by the inventors that in order toachieve the above results, the hindrance portions should comprise ratherminute elements, and not the huge structural components disclosed in theart. Such huge structural components render respective fasteners to beirreversibly inserted into slots. Any attempt to extract these fastenersfrom the side of the panel that they were, inserted would result indestruction of the fasteners.

[0089] According to this invention, the hindrance portions 29 a and 29 bmay comprise minute elements, such as ripples, upward solid bentextensions parallel to the peaks and the recesses, knurled regions, bentteeth, each having a depth, the depth of which does not exceedpreferably 0.2 mm, and more preferably 0.1 mm. Any person of ordinaryskill in the art would not expect that elements having such minutedepths would have such great impact in force balances as theaforementioned ones.

[0090] The depth for any element is substantially defined in the samemanner as defined at a later point for the ripples.

[0091] Although this invention includes any structure which satisfiesthe claims, such as for example upward solid bent extensions parallel tothe peaks and the recesses, knurled regions, bent teeth, as described inat least one of the provisional patent applications 60/301,364, filedJun. 25, 2001, 60/327,814, filed Oct. 9, 2001, and 60/353,515, filedFeb. 1, 2002, and as long as their depth does not exceed 0.2 mm, themost preferable configuration is one that comprises at most threeripples having a preferable depth not exceeding 0.2 mm, and morepreferably not exceeding 0.1 mm. It is more preferable that thehindrance portion comprises not more than two ripples, and even morepreferable one ripple. Structures with one to three two-sided ripples 30are shown in FIGS. 3B to 3D, respectively.

[0092]FIG. 2 illustrates a spring fastener 10 according to thisinvention, wherein the hindrance portion 29 comprises one two-sidedripple 30 and bent barbs 36.

[0093] The most efficient and effective case, however, according to thisinvention, is the use of only one single-sided ripple 30, as shown forexample in FIGS. 1 and 3A.

[0094] The operation of these embodiments is substantially the same asthe operation of the previous embodiments.

[0095] It is preferable that each ripple 30 is in the form of adepression, as better shown in FIG. 5. The depression has a deepest partZ, a front side 32, a back side 34, and a width W1. The hindranceportion 29 has a surface E, and the depth D of each ripple 30 is definedas the distance between the surface E of the hindrance portion 29 andthe deepest part Z of the respective ripple 30.

[0096] For better performance, the ripple width is larger than the depthof the ripple, and preferably the ripple width is at least twice thesize of the depth of the ripple. The ripple width is preferably in therange of 0.1 to 0.5 mm and the ripple depth is in the range of 0.01 to0.1 mm, as aforementioned.

[0097] In a preferred embodiment, the back side 34 of the ripple 30 issubstantially linear and has a slope S in the range of 15 to 30 degreeswith regard to the general plane of the surface E of the hindranceportion 29, and it is also preferable that the front side 32 has ahigher slope than the back side. The slope of the front side is measuredin the same manner as the slope of the back side. Thus, if the frontside 32 is substantially perpendicular to the surface E, the slope issubstantially 0 degrees, while if the front side 32 is substantiallyparallel to the plane of surface E and the continuation of the deepestpart Z, it is substantially 90 degrees.

[0098] It is, however, highly preferable that the back side 34 has theform of a curvature with a gradually decreasing slope. For example, thegradually decreasing slope of back side 34 may have the shape of an arccorresponding to an angle A1, preferably in the range of 50-70 degrees,with a radius R, preferably in the range of 0.03-0.05 mm., as bettershown in FIG. 5A.

[0099] This configuration is of extreme importance in most occasions,because during vibrations, the edges 51 of the slot 50 (FIG. 4C) slidesmoothly on the engagement regions 28 as well as the hindrance portions29 during operation, and when they reach the back sides 34 of thesingle-sided ripples 30 (FIG. 5A), they continue sliding smoothlyfinding increasingly higher resistance in a continuous manner, whicheliminates any rattling noises. Such rattling noises would be present ina case that the edges 51 would hit abrupt obstacles or would suddenlyjump down, even without hitting such obstacles.

[0100] The barbs are preferably selected from a group consistingessentially of:

[0101] first barbs 36 a being outer barbs, and second barbs 36 b beinginner barbs, as better shown in FIGS. 6 (blank before forming) and 6A(side view);

[0102] first barbs 36 a being outside outer barbs, and second barbs 36 bbeing inside outer barbs, as better shown in FIG. 7 (blank beforeforming); and

[0103] first barbs 36 a being inner barbs, and second barbs 36 b beinginner barbs, as better shown in FIG. 8 (blank before forming).

[0104] In operation, the barbs engage on the rib 46 of the first part44, and when an adequate pulling force is applied on the firs part 44,the fastener remains on said first part 44, but is extracted from theslot 50.

[0105] The spring fastener 10 may also comprise relief openings 42 a and42 b in the vicinity of the bottom 16 of the spring fastener 10, asbetter shown in FIG. 6 (blank before forming). These relief openingsfacilitate the insertion of the fastener into the slot 50.

[0106] The spring fastener 10 may further comprise additional lowerbarbs 40 a and 40 b pointing inwardly and originating form the vicinityof the bottom portion 16 of the first side and the second side,respectively, of the fastener 10, as better shown in FIG. 9 (blankbefore forming).

[0107] In another embodiment, better illustrated in FIG. 10 (blankbefore forming), the first side of the spring fastener 10 has only oneupper barb 36 a and one lower barb 40 a, while the second side also hasalso only one upper barb 36 b and only one lower barb 40 b, in a mannerthat the upper barb of one side faces the lower barb of the other sideand vice versa.

[0108] The barbs 36 may have variable width along their length, asillustrated in for example in FIGS. 6-10, or they may have substantiallythe same width along their length as better shown in FIG. 11. Further,the front points of the barbs 36 may be toothed, as illustrated in FIG.12.

[0109] Regarding outside outer barbs 36, it is preferable that theirfront points 38 are at a distance C from the second side 14 smaller thanthe thickness T of the material from which the spring fastener 10 ismade, as better shown in FIG. 1A. This is to avoid interconnection ofthe fasteners, when said fasteners are stored in bulk.

[0110] It is preferable that the barbs are cut from their respectiveside, are flexible, and bent in the vicinity of their respective frontend as described for example in U.S. Pat. No. 6,279,207 B1, which isincorporated herein by reference, and more particularly in FIG. 1 ofsaid patent, with an angle of bent in the range of 5-25 degrees.

[0111] It is also preferable that the fastener 10 has a width W3 (FIG.1A) in the vicinity of the top portion 18 of the fastener 10, which isat least 60%, and more preferably at least 70%, as wide as the slotwidth W2 (FIG. 4C). Thus, it is preferable that the whole fastenercomplies with this requirement, or at least a portion in the vicinity ofthe top. This is to avoid reversal of the direction and failure of thebarbs 36, when and if the rib 46 is forcefully pulled away from thesecond part 48 (FIG. 4B).

[0112] With respect to the engagement regions 28, it is preferable thatthese regions are at least partially wider than the rest of therespective engagement springs 20 (see for example FIG. 6).

[0113] The more barbs are present, or the more bent their front pointsare, the stronger the engagement of the rib 46 in the cavity 19.However, in many occasions it is desirable that this engagement is notso strong so as to destroy the integrity of the fastener or the rib,when an adequate force is applied to separate the fastener 10 from therib 46.

[0114] The spring fasteners 10 of the instant invention may have twoengagement springs 20 at the edges of each side instead of oneengagement spring 20 in substantially the middle portion of each side(see for Example FIG. 10).

[0115] The spring fastener 10 of the instant invention may furthercomprise a molded elastic body 54 at least under the top portion 18 ofsaid spring fastener 10, as better shown in FIG. 13. Such arrangementsare disclosed in U.S. Pat. No. 6,353,981 B1, which is incorporatedherein by reference.

[0116] The operation of this embodiment is similar to the operation ofthe previously described embodiments with the difference that theelastic body provides moderate sealing properties to the fastener whenthe fastener is inserted into the slot.

[0117] In another embodiment, the spring fastener of the instantinvention may further comprise:

[0118] an elastic body 54 comprised of at least a gasket 56, the gasket56 extending away from the closed cavity 19 in the vicinity of the topportion 18 of the fastener 10 and enclosing at least partially thecavity 19; and

[0119] a casing 58 surrounding at least partially the spring fastenerunder the top portion 18, except at least the engagement region 28 ofeach engagement spring 20, the casing 58 also at least partiallysurrounding the cavity 19 and such portion of the elastic body 54 whichat least partially encloses the cavity;

[0120] wherein the casing 58 has lower ultimate elongation, higher Shorehardness, and higher shear strength than the elastic body 54;

[0121] as better shown in FIG. 14.

[0122] The presence of lips 60 improves considerably the sealingproperties of the elastic body.

[0123] Such arrangements are also disclosed in U.S. Pat. No. 6,381,811B2, which is incorporated herein by reference.

[0124] The operation of this embodiment is similar to the operation ofthe previously described embodiments with the difference that thecombination of the elastic body 54 with the casing 58 provideoutstanding sealing properties to the fastener 10 when the fastener 10is inserted into the slot 50, and the casing itself facilitates theinsertion of the fastener 10 into the slot 50.

[0125] According to the present invention, any embodiments of fastenersdescribed above and their equivalents may be used in any assembly inwhich the first part and the second part are connected with thefastener, as well as in any vehicle comprising such an assembly or sucha fastener or its equivalents.

[0126] It should also be understood that the miscellaneous embodimentsand features of the instant invention may be used in any combination orby themselves in other articles or devices, where they may be needed.

[0127] Examples of embodiments demonstrating the operation of theinstant invention, have been given for illustration purposes only, andshould not be construed as restricting the scope or limits of thisinvention in any way.

What is claimed is:
 1. A spring fastener comprising a first side and asecond side opposite the first side, the first side connected to thesecond side thereby forming a U-shaped structure having a cavity betweenthe first side and the second side, a bottom portion wherein the firstside and the second side are connected, and a top portion, the firstside comprising first barbs having first front ends, and a firstengagement spring, the first engagement spring connected to the firstside in the vicinity of the bottom portion, the second side comprisingsecond barbs second front ends, and a second engagement spring, thesecond engagement spring connected to the second side in the vicinity ofthe bottom portion, each of the first and second engagement springshaving a recess and a free end in the vicinity of the top portion, eachspring also comprising a peak and an engagement region with a hindranceportion between the recess and the peak, the hindrance portion providingincreased removal force, when the fastener is pulled by a rib of a firstpart engaged to the first and second barbs, after the fastener has beeninserted into a slot of a second part, the slot having a slot width andedges on which edges the engagement region is engaged, the increasedremoval force being due to the hindrance portion, and wherein thefastener can be extracted when pulled by the rib without damage to saidfastener.
 2. A spring fastener as defined in claim 1, wherein thehindrance portion comprises one structure selected from ripple, siderib, upward solid bent extension parallel to the peak and the recess,knurled region, bent teeth, each having a depth, and a combinationthereof.
 3. A spring fastener as defined in claim 2, wherein the depthof the ripple, the side rib, the upward solid bent extension which isparallel to the peak, the knurled region, and the bent teeth is smallerthan 0.2 mm.
 4. A spring fastener as defined in claim 2, wherein eachripple has the form of a depression, the depression having a deepestpart, a front side, a back side and a width, and the hindrance portionhas a surface, comprises not more than three ripples, and wherein thedepth of each ripple is the distance between the surface of thehindrance portion and the deepest part of the respective ripple.
 5. Aspring fastener as defined in claim 4, wherein hindrance portioncomprises not more than two ripples.
 6. A spring fastener as defined inclaim 5, wherein the hindrance portion comprises only one ripple.
 7. Aspring fastener as defined in claim 6, wherein the ripple width islarger than the depth of the ripple.
 8. A spring fastener as defined inclaim 7, wherein the ripple width is at least twice the size of thedepth of the ripple.
 9. A spring fastener as defined in claim 7, whereinthe ripple width is in the range of 0.1 to 0.5 mm and the ripple depthis in the range of 0.01 to 0.1 mm.
 10. A spring fastener as defined inclaim 4, wherein the back side has a slope in the range of 15 to 30degrees with regard to the general plane of the hindrance portion.
 11. Aspring fastener as defined in claim 4, wherein the front side has ahigher slope than the back side.
 12. A spring fastener as defined inclaim 6, wherein the ripple has only a back side, substantially lackinga front side.
 13. A spring fastener as defined in claim 12, wherein theback side has the form of a curvature with a gradually decreasing slope.14. A spring fastener as defined in claim 13, wherein the graduallydecreasing slope has the shape of an arc in the range of 50-70 degreeswith a radius in the range of 0.03-0.05 mm.
 15. A spring fastener asdefined in claim 1, wherein the barbs are selected from a groupconsisting essentially of: first barbs being outer barbs and secondbarbs being inner barbs; first barbs being outside outer barbs andsecond barbs being inside outer barbs; and first barbs being inner barbsand second barbs being inner barbs.
 16. A spring fastener as defined inclaim 4, wherein the barbs are selected from a group consistingessentially of: first barbs being outer barbs and second barbs beinginner barbs; first barbs being outside outer barbs and second barbsbeing inside outer barbs; and first barbs being inner barbs and secondbarbs being inner barbs.
 17. A spring fastener as defined in claim 12,wherein the barbs are selected from a group consisting essentially of:first barbs being outer barbs and second barbs being inner barbs; firstbarbs being outside outer barbs and second barbs being inside outerbarbs; and first barbs being inner barbs and second barbs being innerbarbs.
 18. A spring fastener as defined in claim 13, wherein the barbsare selected from a group consisting essentially of: first barbs beingouter barbs and second barbs being inner barbs; first barbs beingoutside outer barbs and second barbs being inside outer barbs; and firstbarbs being inner barbs and second barbs being inner barbs.
 19. A springfastener as defined in claim 15, wherein at least one barb is cut fromits respective side, flexible, and bent at its respective front end. 20.A spring fastener as defined in claim 16, wherein at least one barb iscut from its respective side, flexible, and bent at its respective frontend.
 21. A spring fastener as defined in claim 17, wherein at least onebarb is cut from its respective side, flexible, and bent at itsrespective front end.
 22. A spring fastener as defined in claim 18,wherein at least one barb is cut from its respective side, flexible, andbent at its respective front end.
 23. A spring fastener as defined inclaim 15, wherein the material from which the spring fastener has athickness, and the front points of the outside outer barbs are at adistance from the second side smaller than the thickness of saidmaterial.
 24. A spring fastener as defined in claim 18, wherein thematerial from which the spring fastener has a thickness, and the frontpoints of the outside outer barbs are at a distance from the second sidesmaller than the thickness of said material.
 25. A spring fastener asdefined in claim 22, wherein the material from which the spring fastenerhas a thickness, and the front points of the outside outer barbs are ata distance from the second side smaller than the thickness of saidmaterial.
 26. A spring fastener as defined in claim 1, wherein thefastener has a width in the vicinity of the top portion of the fastenerwhich is at least 60% as wide as the slot width.
 27. A spring fasteneras defined in claim 1, wherein the engagement region is at leastpartially wider than the rest of the engagement spring.
 28. A springfastener as defined in claim 4, wherein the engagement region is atleast partially wider than the rest of the engagement spring.
 29. Aspring fastener as defined in claim 12, wherein the engagement region isat least partially wider than the rest of the engagement spring.
 30. Aspring fastener as defined in claim 13, wherein the engagement region isat least partially wider than the rest of the engagement spring.
 31. Aspring fastener as defined in claim 1, further comprising additionallower barbs pointing inwardly and originating form the vicinity of thebottom portions of the first side and the second side of the fastener.32. A spring fastener as defined in claim 1, wherein each side of thespring fastener has only one upper barb and one lower barb, the upperbarb of one side facing the lower barb of the other side and vice versa.33. A spring fastener as defined in claim 1, further comprising a reliefopening in the vicinity of the bottom of the spring fastener.
 34. Anassembly comprising: a spring fastener comprising a first side and asecond side opposite the first side, the first side connected to thesecond side thereby forming a U-shaped structure having a cavity betweenthe first side and the second side, a bottom portion wherein the firstside and the second side are connected, and a top portion, the firstside comprising first barbs having first front ends, and a firstengagement spring, the first engagement spring connected to the firstside in the vicinity of the bottom portion, the second side comprisingsecond barbs second front ends, and a second engagement spring, thesecond engagement spring connected to the second side in the vicinity ofthe bottom portion, each of the first and second engagement springshaving a recess and a free end in the vicinity of the top portion, eachspring also comprising a peak and an engagement region with a hindranceportion between the recess and the peak; a first part comprising a ribinserted into the cavity of the spring fastener and engaged to the firstand second barbs; and a second part comprising a slot, the slot having awidth and edges, the fastener being disposed in the slot in a mannerthat the edges of said slot are engaged to the engagement regions of thespring fastener; with the requirement that by pulling the rib, thefastener is extracted from the slot without damage to the fastener, andwith a higher force than a force required in the absence of thehindrance portion.
 35. An assembly as defined in claim 34, wherein thehindrance portion comprises one structure selected from ripple, siderib, upward solid bent extension parallel to the peak and the recess,knurled region, bent teeth, each having a depth, and a combinationthereof.
 36. An assembly as defined in claim 35, wherein the depth ofthe ripple, the side rib, the upward solid bent extension which isparallel to the peak, the knurled region, and the bent teeth is smallerthan 0.2 mm.
 37. An assembly as defined in claim 35, wherein each ripplehas the form of a depression, the depression having a deepest part, afront side, a back side and a width, and the hindrance portion has asurface, comprises not more than three ripples, and wherein the depth ofeach ripple is the distance between the surface of the hindrance portionand the deepest part of the respective ripple.
 38. An assembly asdefined in claim 37, wherein hindrance portion comprises not more thantwo ripples.
 39. An assembly as defined in claim 38, wherein thehindrance portion comprises only one ripple.
 40. An assembly as definedin claim 39, wherein the ripple width is larger than the depth of theripple.
 41. An assembly as defined in claim 40, wherein the ripple widthis at least twice the size of the depth of the ripple.
 42. An assemblyas defined in claim 40, wherein the ripple width is in the range of 0.1to 0.5 mm and the ripple depth is in the range of 0.01 to 0.1 mm.
 43. Anassembly as defined in claim 37, wherein the back side has a slope inthe range of 15 to 30 degrees with regard to the general plane of thehindrance portion.
 44. An assembly as defined in claim 37, wherein thefront side has a higher slope than the back side.
 45. An assembly asdefined in claim 39, wherein the ripple has only a back side,substantially lacking a front side.
 46. An assembly as defined in claim45, wherein the back side has the form of a curvature with a graduallydecreasing slope.
 47. An assembly as defined in claim 46, wherein thegradually decreasing slope has the shape of an arc in the range of 50-70degrees with a radius in the range of 0.03-0.05 mm.
 48. An assembly asdefined in claim 34, wherein the barbs are selected from a groupconsisting essentially of: first barbs being outer barbs and secondbarbs being inner barbs; first barbs being outside outer barbs andsecond barbs being inside outer barbs; and first barbs being inner barbsand second barbs being inner barbs.
 49. An assembly as defined in claim37, wherein the barbs are selected from a group consisting essentiallyof: first barbs being outer barbs and second barbs being inner barbs;first barbs being outside outer barbs and second barbs being insideouter barbs; and first barbs being inner barbs and second barbs beinginner barbs.
 50. An assembly as defined in claim 45, wherein the barbsare selected from a group consisting essentially of: first barbs beingouter barbs and second barbs being inner barbs; first barbs beingoutside outer barbs and second barbs being inside outer barbs; and firstbarbs being inner barbs and second barbs being inner barbs.
 51. Anassembly as defined in claim 46, wherein the barbs are selected from agroup consisting essentially of: first barbs being outer barbs andsecond barbs being inner barbs; first barbs being outside outer barbsand second barbs being inside outer barbs; and first barbs being innerbarbs and second barbs being inner barbs.
 52. An assembly as defined inclaim 48, wherein at least one barb is cut from its respective side,flexible, and bent at its respective front end.
 53. An assembly asdefined in claim 49, wherein at least one barb is cut from itsrespective side, flexible, and bent at its respective front end.
 54. Anassembly as defined in claim 50, wherein at least one barb is cut fromits respective side, flexible, and bent at its respective front end. 55.An assembly as defined in claim 51, wherein at least one barb is cutfrom its respective side, flexible, and bent at its respective frontend.
 56. An assembly as defined in claim 48, wherein the material fromwhich the spring fastener has a thickness, and the front points of theoutside outer barbs are at a distance from the second side smaller thanthe thickness of said material.
 57. An assembly as defined in claim 51,wherein the material from which the spring fastener has a thickness, andthe front points of the outside outer barbs are at a distance from thesecond side smaller than the thickness of said material.
 58. An assemblyas defined in claim 55, wherein the material from which the springfastener has a thickness, and the front points of the outside outerbarbs are at a distance from the second side smaller than the thicknessof said material.
 59. An assembly as defined in claim 34, wherein thefastener has a width in the vicinity of the top portion of the fastenerwhich is at least 60% as wide as the slot width.
 60. An assembly asdefined in claim 34, wherein the engagement region is at least partiallywider than the rest of the engagement spring.
 61. An assembly as definedin claim 37, wherein the engagement region is at least partially widerthan the rest of the engagement spring.
 62. An assembly as defined inclaim 45, wherein the engagement region is at least partially wider thanthe rest of the engagement spring.
 63. An assembly as defined in claim46, wherein the engagement region is at least partially wider than therest of the engagement spring.
 64. An assembly as defined in claim 34,wherein the spring fastener further comprises additional lower barbspointing inwardly and originating form the vicinity of the bottomportions of the first side and the second side of the fastener.
 65. Anassembly as defined in claim 34, wherein each side of the springfastener has only one upper barb and one lower barb, the upper barb ofone side facing the lower barb of the other side and vice versa.
 66. Anassembly as defined in claim 34, wherein the spring fastener furthercomprises a relief opening in the vicinity of the bottom of the springfastener.
 67. A vehicle comprising an assembly, the assembly comprising:a spring fastener comprising a first side and a second side opposite thefirst side, the first side connected to the second side thereby forminga U-shaped structure having a cavity between the first side and thesecond side, a bottom portion wherein the first side and the second sideare connected, and a top portion, the first side comprising first barbshaving first front ends, and a first engagement spring, the firstengagement spring connected to the first side in the vicinity of thebottom portion, the second side comprising second barbs second frontends, and a second engagement spring, the second engagement springconnected to the second side in the vicinity of the bottom portion, eachof the first and second engagement springs having a recess and a freeend in the vicinity of the top portion, each spring also comprising apeak and an engagement region with a hindrance portion between therecess and the peak; a first part comprising a rib inserted into thecavity of the spring fastener and engaged to the first and second barbs;and a second part comprising a slot, the slot having a width and edges,the fastener being disposed in the slot in a manner that the edges ofsaid slot are engaged to the engagement regions of the spring fastener;with the requirement that by pulling the rib, the fastener is extractedfrom the slot without damage to the fastener, and with a higher forcethan a force required in the absence of the hindrance portion.
 68. Avehicle as defined in claim 67, wherein the hindrance portion comprisesone structure selected from ripple, side rib, upward solid bentextension parallel to the peak and the recess, knurled region, bentteeth, each having a depth, and a combination thereof.
 69. A vehicle asdefined in claim 68, wherein the depth of the ripple, the side rib, theupward solid bent extension which is parallel to the peak, the knurledregion, and the bent teeth is smaller than 0.2 mm.
 70. A vehicle asdefined in claim 68, wherein each ripple has the form of a depression,the depression having a deepest part, a front side, a back side and awidth, and the hindrance portion has a surface, comprises not more thanthree ripples, and wherein the depth of each ripple is the distancebetween the surface of the hindrance portion and the deepest part of therespective ripple.
 71. A vehicle as defined in claim 70, whereinhindrance portion comprises not more than two ripples.
 72. A vehicle asdefined in claim 71, wherein the hindrance portion comprises only oneripple.
 73. A vehicle as defined in claim 72, wherein the ripple widthis larger than the depth of the ripple.
 74. A vehicle as defined inclaim 73, wherein the ripple width is at least twice the size of thedepth of the ripple.
 75. A vehicle as defined in claim 73, wherein theripple width is in the range of 0.1 to 0.5 mm and the ripple depth is inthe range of 0.01 to 0.1 mm.
 76. A vehicle as defined in claim 70,wherein the back side has a slope in the range of 15 to 30 degrees withregard to the general plane of the hindrance portion.
 77. A vehicle asdefined in claim 70, wherein the front side has a higher slope than theback side.
 78. A vehicle as defined in claim 72, wherein the ripple hasonly a back side, substantially lacking a front side.
 79. A vehicle asdefined in claim 78, wherein the back side has the form of a curvaturewith a gradually decreasing slope.
 80. A vehicle as defined in claim 79,wherein the gradually decreasing slope has the shape of an arc in therange of 50-70 degrees with a radius in the range of 0.03-0.05 mm.
 81. Avehicle as defined in claim 67, wherein the barbs are selected from agroup consisting essentially of: first barbs being outer barbs andsecond barbs being inner barbs; first barbs being outside outer barbsand second barbs being inside outer barbs; and first barbs being innerbarbs and second barbs being inner barbs.
 82. A vehicle as defined inclaim 70, wherein the barbs are selected from a group consistingessentially of: first barbs being outer barbs and second barbs beinginner barbs; first barbs being outside outer barbs and second barbsbeing inside outer barbs; and first barbs being inner barbs and secondbarbs being inner barbs.
 83. A vehicle as defined in claim 78, whereinthe barbs are selected from a group consisting essentially of: firstbarbs being outer barbs and second barbs being inner barbs; first barbsbeing outside outer barbs and second barbs being inside outer barbs; andfirst barbs being inner barbs and second barbs being inner barbs.
 84. Avehicle as defined in claim 79, wherein the barbs are selected from agroup consisting essentially of: first barbs being outer barbs andsecond barbs being inner barbs; first barbs being outside outer barbsand second barbs being inside outer barbs; and first barbs being innerbarbs and second barbs being inner barbs.
 85. A vehicle as defined inclaim 81, wherein at least one barb is cut from its respective side,flexible, and bent at its respective front end.
 86. A vehicle as definedin claim 82, wherein at least one barb is cut from its respective side,flexible, and bent at its respective front end.
 87. A vehicle as definedin claim 83, wherein at least one barb is cut from its respective side,flexible, and bent at its respective front end.
 88. A vehicle as definedin claim 84, wherein at least one barb is cut from its respective side,flexible, and bent at its respective front end.
 89. A vehicle as definedin claim 81, wherein the material from which the spring fastener has athickness, and the front points of the outside outer barbs are at adistance from the second side smaller than the thickness of saidmaterial.
 90. A vehicle as defined in claim 84, wherein the materialfrom which the spring fastener has a thickness, and the front points ofthe outside outer barbs are at a distance from the second side smallerthan the thickness of said material.
 91. A vehicle as defined in claim88, wherein the material from which the spring fastener has a thickness,and the front points of the outside outer barbs are at a distance fromthe second side smaller than the thickness of said material.
 92. Avehicle as defined in claim 67, wherein the fastener has a width in thevicinity of the top portion of the fastener which is at least 60% aswide as the slot width.
 93. A vehicle as defined in claim 67, whereinthe engagement region is at least partially wider than the rest of theengagement spring.
 94. A vehicle as defined in claim 70, wherein theengagement region is at least partially wider than the rest of theengagement spring.
 95. A vehicle as defined in claim 78, wherein theengagement region is at least partially wider than the rest of theengagement spring.
 96. A vehicle as defined in claim 79, wherein theengagement region is at least partially wider than the rest of theengagement spring.
 97. A vehicle as defined in claim 67, wherein thespring fastener further comprises additional lower barbs pointinginwardly and originating form the vicinity of the bottom portions of thefirst side and the second side of the fastener.
 98. A vehicle as definedin claim 67, wherein each side of the spring fastener has only one upperbarb and one lower barb, the upper barb of one side facing the lowerbarb of the other side and vice versa.
 99. A vehicle as defined in claim67, wherein the spring fastener further comprises a relief opening inthe vicinity of the bottom of the spring fastener.
 100. A fastener asdefined in claim 1, wherein a force to insert the rib of the first partinto the cavity of the spring fastener is less than 40 lbs; a force toinsert the spring fastener into the slot of the second part is less that30 lbs; and a force to extract the spring fastener from the slot is inthe range of 30-100 lbs.
 101. An assembly as defined in claim 34,wherein a force to insert the rib of the first part into the cavity ofthe spring fastener is less than 40 lbs; a force to insert the springfastener into the slot of the second part is less that 30 lbs; and aforce to extract the spring fastener from the slot is in the range of30-100 lbs.
 101. A vehicle as defined in claim 67, wherein a force toinsert the rib of the first part into the cavity of the spring fasteneris less than 40 lbs; a force to insert the spring fastener into the slotof the second part is less that 30 lbs; and a force to extract thespring fastener from the slot is in the range of 30-100 lbs.
 102. Aspring fastener as defined in claim 1, further comprising a moldedelastic body under the top portion of said spring fastener.
 103. Anassembly as defined in claim 34, wherein the fastener further comprisesa molded elastic body under the top portion of said spring fastener.104. A vehicle as defined in claim 67, wherein the fastener furthercomprises a molded elastic body under the top portion of said springfastener.
 105. A spring fastener as defined in claim 1, furthercomprising: an elastic body comprised of at least a gasket, the gasketextending away from the closed cavity in the vicinity of the top portionof the fastener and enclosing at least partially the cavity; a casingsurrounding at least partially the spring fastener under the topportion, except at least the engagement section of each engagementspring, the casing also at least partially surrounding the cavity andsuch portion of the elastic body which at least partially encloses thecavity; wherein the casing has lower ultimate elongation, higher Shorehardness, and higher shear strength than the elastic body.
 106. Anassembly as defined in claim 34, wherein the fastener further comprises:an elastic body comprised of at least a gasket, the gasket extendingaway from the closed cavity in the vicinity of the top portion of thefastener and enclosing at least partially the cavity; a casingsurrounding at least partially the spring fastener under the topportion, except at least the engagement section of each engagementspring, the casing also at least partially surrounding the cavity andsuch portion of the elastic body which at least partially encloses thecavity; wherein the casing has lower ultimate elongation, higher Shorehardness, and higher shear strength than the elastic body.
 107. Avehicle as defined in claim 67, wherein the fastener further comprises:an elastic body comprised of at least a gasket, the gasket extendingaway from the closed cavity in the vicinity of the top portion of thefastener and enclosing at least partially the cavity; a casingsurrounding at least partially the spring fastener under the topportion, except at least the engagement section of each engagementspring, the casing also at least partially surrounding the cavity andsuch portion of the elastic body which at least partially encloses thecavity; wherein the casing has lower ultimate elongation, higher Shorehardness, and higher shear strength than the elastic body.